import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 高生平
 * Date: 2025-09-13
 * Time: 20:07
 */
public class Test {
    public static int sequentialSearch (int[] array, int k) {
        for (int i = 0; i < array.length; i++) {
            if(array[i] == k) {
                return i;
            }
        }
        return -1;//如果没找到，可以返回-1，因为没有下标是-1的
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] array = new int[n];
        for (int i = 0; i < n; i++) {
            array[i] = sc.nextInt();
        }
        int k = sc.nextInt();
        System.out.println(sequentialSearch(array, k));
    }
}
